SECTION 4
CESSNA
NORMAL PROCEDURES
MODEL 172RG
With Preheat:
1.
With ignition switch OFF and throttle closed, prime the engine two
to four strokes as the propeller is being turned over by hand.
NOTE
Use heavy strokes of primer for best atomization of fuel.
After priming, push primer all the way in and turn to
locked position to avoid possibility of engine drawing fuel
through the primer.
2.
Propeller Area -- CLEAR.
3.
Avionics Power Switch -- OFF.
4.
Master Switch -- ON.
5.
Mixture -- FULL RICH.
6.
Throttle -- OPEN 1/4 INCH.
7.
Ignition Switch -- START.
8.
Release ignition switch to BOTH when engine starts.
9.
Oil Pressure -- CHECK.
Without Preheat:
1.
Prime the engine four to eight strokes while the propeller is being
turned by hand with the throttle closed. Leave the primer charged
and ready for a stroke.
2.
Propeller Area -- CLEAR.
3.
Avionics Power Switch -- OFF.
4.
Master Switch -- ON.
5.
Mixture -- FULL RICH.
6.
Pump throttle rapidly to full open twice. Return to 1/4 inch open
position.
7.
Ignition Switch -- START.
8.
Release ignition switch to BOTH when engine starts.
9.
Continue to prime engine until it is running smoothly, or alter-
nately, pump throttle rapidly over first 1/4 of total travel.
10.
Oil Pressure -- CHECK.
11.
Pull carburetor heat knob full on after engine has started. Leave on
until engine is running smoothly.
12.
Primer -- LOCK.
NOTE
If the engine does not start during the first few attempts, or
if engine firing diminishes in strength, it is probable that
the spark plugs have been frosted over. Preheat must be
used before another start is attempted.
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1 July 1979
CESSNA
SECTION 4
MODEL 172RG
NORMAL PROCEDURES
CAUTION
Excessive pumping of the throttle may cause raw fuel to
accumulate in the intake manifold, creating a fire hazard
in the event of a backfire. If this occurs, maintain a
cranking action to suck flames into the engine. An outside
attendant with a fire extinguisher is advised for cold starts
without preheat.
OPERATION
During cold weather operations, no indication will be apparent on the
oil temperature gage prior to takeoff if outside air temperatures are very
cold. After a suitable warm-up period (2 to 5 minutes at 1000 RPM),
accelerate the engine several times to higher engine RPM. If the engine
accelerates smoothly and the oil pressure remains normal and steady, the
airplane is ready for takeoff.
Rough engine operation in cold weather can be caused by a combina-
tion of an inherently leaner mixture due to the dense air and poor
vaporization and distribution of the fuel-air mixture to the cylinders. The
effects of these conditions are especially noticeable during operation on
one magneto in ground checks where only one spark plug fires in each
cylinder.
For optimum operation of the engine in cold weather, the appropriate
use of carburetor heat may be necessary. The following procedures are
indicated as a guideline:
1.
Use the minimum carburetor heat required for smooth operation in
takeoff, climb, and cruise.
NOTE
Care should be exercised when using partial carburetor
heat to avoid icing. Partial heat may raise the carburetor
air temperature to 0° to 21°C range where icing is critical
under certain atmospheric conditions.
2.
If the airplane is equipped with a carburetor air temperature gage,
it can be used as a reference in maintaining carburetor air
temperature at or slightly above the top of the yellow arc by
application of carburetor heat.
HOT WEATHER OPERATION
The general warm temperature starting information in this section is
1 July 1979
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